MARYLAND GEOLOGICAL SURVEY 591 



of the shell where they are narrower than the interspaces, the ribs upon the 

 auriculations are narrower, closer together, and more nodose than upon 

 the body of the shell, though in some examples, especially the larger ones, 

 they are inconspicuous. The surface is also marked by more or less 

 irregular, concentric lines of growth. 



"Remarks. The shells which are made the types of this species were 

 identified and illustrated by Whitfield as P. tenuitestus, but an exami- 

 nation of Gabb's type of that species has shown that Whitfield's identifica- 

 tion was incorrect, the true P. tenuitestus being the same as the specimens 

 described as P. planicostatus by that author. This species differs from 

 P. tenuitestus of the same fauna, in being proportionally higher, nar- 

 rower, and more convex, with the radiating ribs nodose, and proportion- 

 ally broader with narrower interspaces and with the concentric markings 

 coarser and less regular." Weller, 1907. 



A fragment of a nmlticostate scabrous Pecten occurs at Brooks estate, 

 Prince George's County, and may perhaps indicate the former presence of 

 this species in Maryland. Fragments of another species, possibly closely 

 allied with P. whitfieldi Weller, were collected in the Matawan at Camp 

 Fox on the Chesapeake and Delaware Canal. The Matawan form has 

 much more numerous costa3 which are rendered scabrous by the over- 

 riding concentric sculpture. 



Occurrence. MOXMOUTH FORMATION. Brooks estate near Seat Pleas- 

 ant, Prince George's County. 



Collections. Maryland Geological Survey, Columbia University, New 

 Jersey Geological Survey. 



Outside Distribution. Monmouth Formation. Navesink marl, New 

 Jersey. 



PECTEX VEXUSTUS Morton 

 Plate XXXIV, Figs. 6, 7 



Pecten venustus Morton, 1833, Am. Jour. Sci., 1st ser., vol. xxiii, p. 293, pi. 



v, fig. 7. 

 Pecten venustus Morton, 1834, Syn. Org. Rem. Cret. Group, U. S., p. 58, pi. 



v, fig. 7. 

 Pecten venustus Meek, 1864, Check List Inv. Fossils, N. A., Cret. and Jur., 



p. 7. 



